hmmm....no idea about that MArcia... we changed formula brands with MAtilda but she was only having one to two bottles a day at that time... She's on Karicare thickened HA-AR and we use warm colled boiled water that has been put in the fridge and then heated up in the microwave & then we add the formula to it, once it cools off it gets heaps thicker so I don't know about mixing it up cool, I do know that Matilda likes it best at room temp and not too warm though so we don't really heat it up much in the microwave....

HTH